Acuray founder John Adler laughs and says his free-spirited son, Trip Adler, couldn't have done anything aside from becoming an entrepreneur. "Entrepreneurs have no rules," he points out. One piece of advice he does give his son: Never give up the title of CEO. It's one of the hardest things to learn, he confesses. Trip Adler, CEO of Scribd, concurs. He explains that in many cases, it is the founder who is able to provide the vision to effectively direct product development.